To investigate the neural mechanisms underlying intellectually gifted children, electroencephalograms (EEG) were recorded while 13 intellectually gifted children and 13 average children accomplished a 1-back working memory task. The results showed that intellectually gifted children elicited significantly shorter P3 latency than their intellectually average peers. These results support the neural efficiency theory that intellectually gifted individual can use their brain more efficiently

The ability to form and access memories of our experiences involves complex neural mechanisms at both the cellular and systems levels. Animal and human (including lesion and neuroimaging) studies have evidenced a critical role for the hippocampus and connected brain regions in these processes. The current chapter will review the role of the hippocampus in the different stages of long-term memory, namely, encoding, consolidation, and retrieval. Specifically, this chapter will illustrate how the hippocampus, in conjunction with other brain regions, supports these processes, giving rise to our rich experience of remembering.

Songbirds, such as zebra finches, learn their songs from a ‘tutor’ (usually the father), early in life. There are strong parallels between the behavioural, cognitive and neural processes that underlie vocal learning in humans and songbirds. In both cases there is a sensitive period for auditory learning, during which the young individuals memorize the vocalizations of adult conspecifics to which they are exposed. After this memorization phase, vocal learning proceeds through a sensorimotor learning phase that is called ‘babbling’ in human infants and ‘subsong' in songbirds. There are homologies between the brains of birds and mammals, which makes the songbird a suitable model organism for studying the neural mechanisms of vocal learning and memory. In songbirds, a network of interconnected nuclei, known as the ‘song system’ is involved in song production and sensorimotor learning. In contrast, it has been suggested that a forebrain region outside the song system, the caudomedial nidopallium (NCM), may contain the neural substrate for the representation of auditory memory acquired in the first phase of song learning. In zebra finches, males learn their vocalisations (calls and songs) while females do not sing, but produce only unlearned calls. Studying the perception of vocalisations in males as well as females may provide clues about how the neural substrate of perception and memory functions in both sexes. This thesis describes three studies investigating the neural mechanisms of auditory memory and perception in zebra finches. First, I have shown that, in adult zebra finch males, the NCM is necessary for recognition of tutor song, but not for song production. In addition, I demonstrated that in juvenile zebra finches the NCM is activated during auditory memory formation. These experiments confirm that the NCM is the likely neural substrate for the representation of tutor song memory. In juvenile male zebra finches, there is neuronal activation in the song system of birds that are singing themselves but not when they are exposed to songs. Thus, in songbirds the cognitive systems underlying vocal production and auditory recognition memory are subserved by distinct brain regions in juveniles as well as adults. These brain regions may functionally interact continually throughout life. Finally, I have shown that the neuronal processing of auditory signals such as the long call appears to differ between males and females. Unravelling the underlying processes related to the perception and memorization of vocalisations that differ between males and females can increase our understanding of how vocalisations are learned. The localization of the neural substrate of tutor song memory presented in this thesis is a necessary prerequisite for the investigation of the neural mechanisms of auditory memory at the molecular and cellular level. The dissociation of brain regions involved in vocal production and in memory in the human as well as in the avian brain, suggests convergent evolution of the mechanisms underlying auditory-vocal learning. Thus, by investigating the neural mechanisms underlying birdsong learning, we may gain important insights into the general mechanisms of auditory-vocal learning

Selective attention and working memory are inter-dependent core cognitive functions. It is critical to allocate attention on selected targets during the capacity-limited working memory processes to fulfill the goal-directed behavior. The trends of research on both topics are increasing exponentially in recent years, and it is considered that selective attention and working memory share similar underlying neural mechanisms. Different types of attention orientation in working memory are introduced by distinctive cues, and the means using retrospective cues are strengthened currently as it is manipulating the representation in memory, instead of the perceptual representation. The cognitive and neural mechanisms of the retro-cue effects are further reviewed, as well as the potential molecular mechanism. The frontal-parietal network that is involved in both attention and working memory is also the neural candidate for attention orientation during working memory. Neural oscillations in the gamma and alpha/beta oscillations may respectively be employed for the feedforward and feedback information transfer between the sensory cortices and the association cortices. Dopamine and serotonin systems might interact with each other subserving the communication between memory and attention. In conclusion, representations which attention shifts towards are strengthened, while representations which attention moves away from are degraded. Studies on attention orientation during working memory indicates the flexibility of the processes of working memory, and the beneficial way that overcome the limited capacity of working memory.

Objective: This study investigates the neural mechanisms underlying memory and cognitive control using functional magnetic resonance imaging (fMRI).Methods: We conducted an fMRI study with 30 participants to examine brain activity during tasks involving memory and cognitive control.Results: Significant activation was observed in the prefrontal cortex and parietal lobes during memory and cognitive control tasks.Conclusion: The study highlights critical neural regions involved in memory and cognitive control, suggesting potential targets for cognitive interventions.

Spatial memory is a well-characterized psychological function in both humans and rodents. The combined computations of a network of systems including place cells in the hippocampus, grid cells in the medial entorhinal cortex and head direction cells found in numerous structures in the brain have been suggested to form the neural instantiation of the cognitive map as first described by Tolman in 1948. However, while our understanding of the neural mechanisms underlying spatial representations in adults is relatively sophisticated, we know substantially less about how this network develops in young animals. In this article we briefly review studies examining the developmental time scale that these systems follow. Electrophysiological recordings from very young rats show that directional information is at adult levels at the outset of navigational experience. The systems supporting allocentric memory, however, take longer to mature. This is consistent with behavioral studies of young rats which show that spatial memory based on head direction develops very early but that allocentric spatial memory takes longer to mature. We go on to report new data demonstrating that memory for associations between objects and their spatial locations is slower to develop than memory for objects alone. This is again consistent with previous reports suggesting that adult like spatial representations have a protracted development in rats and also suggests that the systems involved in processing non-spatial stimuli come online earlier.Peer reviewe

Emotional enhancement of memory (EEM) is thought to modulate memory recollection rather than familiarity. However, the contributing factors and neural mechanisms are not well understood. To address these issues, we investigated how valence, arousal, and the amount of devoted attention influence the EEM effect on recollection. We also compared the topological properties among hippocampus- and perirhinal and entorhinal cortex-mediated emotional memory processing networks. Finally, we evaluated the correlations between emotional memory/EEM and inherent properties (i.e., amplitude of low-frequency fluctuation and node degree, efficiency, and betweenness) of the hippocampus and perirhinal and entorhinal cortices in 59 healthy young adults by resting-state functional magnetic resonance imaging. EEM was elicited by incidental encoding, negative images, and positive high-arousal images. The hippocampus was correlated with recollection sensitivity and EEMnegative-high-arousal. The emotional memory processing network mediated by the hippocampus had higher clustering coefficient, local efficiency, and normalized characteristic path length but lower normalized global efficiency than those mediated by the perirhinal and entorhinal cortices. The entorhinal cortex was associated with both recollection and familiarity sensitivity, but showed different correlation patterns. The perirhinal cortex was highly correlated with familiarity sensitivity of negative low-arousal stimuli. These results demonstrate that the EEM effect on memory recollection is influenced by valence, stimulus arousal, and amount of attention involved during encoding. Moreover, the hippocampus and perirhinal and entorhinal cortices play distinct roles in the recollection and familiarity of emotional memory and the EEM effect.

Iconic memory and spatial attention are often considered as distinct topics, but may have functional similarities. Here we provide fMRI evidence for some common underlying neural effects. Participants judged three visual stimuli in one hemifield of a bilateral array comprising six stimuli. The relevant hemifield for partial report was indicated by an auditory cue, administered either before the visual array (pre-cues, spatial attention) or shortly after (post-cues, iconic memory). Pre- and post-cues led to similar activity modulations in lateral occipital cortex, contralateral to the cued side, indicating that readout from iconic memory can have similar neural effects to spatial attention. We also found common bilateral activation of a fronto-parietal network for post-cue and pre-cue trials. These neuroimaging data suggest that some common neural mechanisms underlie selective spatial attention and readout from iconic memory. Some differences were also found, with post-cues leading to higher activity in right middle frontal gyrus

Retrieving particular information from memory facilitates the later retrieval of that information, but also impairs the later retrieval of related, interfering information. It has been theorized that this retrieval-induced forgetting reflects inhibition of interfering memory representations. We used event-related fMRI to investigate the functional neuroanatomy of this impaired retrieval, at the time the impairment is observed. Neural activity differences between impaired and facilitated information occurred in left ventrolateral prefrontal cortex (VLPFC, BA 45 and 47), precuneus (BA 7), and right inferior parietal lobule (IPL, BA 40). Activity in left anterior VLPFC (BA 47) and left posterior temporal cortex (BA 22), regions implicated in the controlled retrieval of weak semantic memory representations, predicted the degree of retrieval-induced forgetting. In contrast, activity in precuneus and right IPL predicted the degree of retrieval-induced facilitation. Our findings demonstrate that impairment of interfering memories and facilitation of practiced memories involve distinct neural processes, and suggest that the impairment reflects inhibition that weakens interfering memory representations

When someone mentions the name of a known person we immediately recall her face and possibly many other traits. This is because we possess the so-called associative memory - the ability to correlate different memories to the same fact or event. Associative memory is such a fundamental and encompassing human ability (and not just human) that the network of neurons in our brain must perform it quite easily. The question is then whether electronic neural networks - electronic schemes that act somewhat similarly to human brains - can be built to perform this type of function. Although the field of neural networks has developed for many years, a key element, namely the synapses between adjacent neurons, has been lacking a satisfactory electronic representation. The reason for this is that a passive circuit element able to reproduce the synapse behaviour needs to remember its past dynamical history, store a continuous set of states, and be "plastic" according to the pre-synaptic and post-synaptic neuronal activity. Here we show that all this can be accomplished by a memory-resistor (memristor for short). In particular, by using simple and inexpensive off-the-shelf components we have built a memristor emulator which realizes all required synaptic properties. Most importantly, we have demonstrated experimentally the formation of associative memory in a simple neural network consisting of three electronic neurons connected by two memristor-emulator synapses. This experimental demonstration opens up new possibilities in the understanding of neural processes using memory devices, an important step forward to reproduce complex learning, adaptive and spontaneous behaviour with electronic neural networks

Laying down a new memory involves activity in a number of brain regions. Here, it is shown that the particular regions associated with successful encoding depend on the way in which memory is probed. Event-related functional magnetic resonance imaging signals were acquired while subjects performed an incidental encoding task on a series of visually presented words denoting objects. A recognition memory test using the Remember/Know procedure to separate responses based on recollection and familiarity followed 1 day later. Critically, half of the studied objects were cued with a corresponding spoken word, and half with a corresponding picture. Regardless of cue, activity in prefrontal and hippocampal regions predicted subsequent recollection of a word. Type of retrieval cue modulated activity in prefrontal, temporal, and parietal cortices. Words subsequently recognized on the basis of a sense of familiarity were at study also associated with differential activity in a number of brain regions, some of which were probe dependent. Thus, observed neural correlates of successful encoding are constrained by type of retrieval cue, and are only fragments of all encoding-related neural activity. Regions exhibiting cue-specific effects may be sites that support memory through the degree of overlap between the processes engaged during encoding and those engaged during retrieval

Although previous studies point to qualitative similarities between working memory (WM) and attention, the degree to which these two constructs rely on shared neural mechanisms remains unknown. Focusing on one such potentially shared mechanism, we tested the hypothesis that selecting an item within WM utilizes similar neural mechanisms as selecting a visible item via a shift of attention. We used fMRI and machine learning to decode both the selection among items visually available and the selection among items stored in WM in human subjects (both sexes). Patterns of activity in visual, parietal, and to a lesser extent frontal cortex predicted the locations of the selected items. Critically, these patterns were strikingly interchangeable; classifiers trained on data during attentional selection predicted selection from WM, and classifiers trained on data during selection from memory predicted attentional selection. Using models of voxel receptive fields, we visualized topographic population activity that revealed gain enhancements at the locations of the externally and internally selected items. Our results suggest that selecting among perceived items and selecting among items in WM share a common mechanism. This common mechanism, analogous to a shift of spatial attention, controls the relative gains of neural populations that encode behaviorally relevant information. SIGNIFICANCE STATEMENT How we allocate our attention to external stimuli that we see and to internal representations of stimuli stored in memory might rely on a common mechanism. Supporting this hypothesis, we demonstrated that not only could patterns of human brain activity predict which items were selected during perception and memory, but that these patterns were interchangeable during external and internal selection. Additionally, this generalized selection mechanism operates by changes in the gains of the neural populations both encoding attended sensory representations and storing relevant memory representations.

Pavlov conditioning is a typical associative memory, which involves associative learning between the gustatory and auditory cortex, known as Pavlov associative memory. Inspired by neural mechanisms and biological phenomena of Pavlov associative memory, this paper proposes a multi-functional memristive Pavlov associative memory circuit. In addition to learning and forgetting, whose rates change with the number of associative learning times, the circuit also achieves other innovative functions. First, consolidation learning, which refers to the continued learning process after acquiring associative memory, changes the rates of learning and forgetting. Secondly, the natural forgetting rate tends to zero when the associative memory has been acquired several times, which means the formation of long-term memory. Thirdly, the generalization and differentiation of associative memory caused by similar stimuli are realized through a simplified memristive feedforward neural network. Besides, this circuit implements the associative learning function of interval stimuli through a simpler structure, which refers to “the longer the stimuli interval, the slower the learning rate”. The above functions are realized by the time interval module, variable rates module, and generalization and differentiation module. It has been shown that the proposed circuit has good robustness, and can reduce the influence of parasitic capacitance, memristive conductance drift, and input noise on circuit functions. Through further research, this circuit is expected to be used in robot platforms to realize human-like perception and associative cognitive functions.

Spatial navigation is a fascinating behavior that is essential for our everyday lives. It involves nearly all sensory systems, it requires numerous parallel computations, and it engages multiple memory systems. One of the key problems in this field pertains to the question of reference frames: spatial information such as direction or distance can be coded egocentrically - relative to an observer - or allocentrically - in a reference frame independent of the observer. While many studies have associated striatal and parietal circuits with egocentric coding and entorhinal/hippocampal circuits with allocentric coding, this strict dissociation is not in line with a growing body of experimental data. In this review, we discuss some of the problems that can arise when studying the neural mechanisms that are presumed to support different spatial reference frames. We argue that the scale of space in which a navigation task takes place plays a crucial role in determining the processes that are being recruited. This has important implications, particularly for the inferences that can be made from animal studies in small scale space about the neural mechanisms supporting human spatial navigation in large (environmental) spaces. Furthermore, we argue that many of the commonly used tasks to study spatial navigation and the underlying neuronal mechanisms involve different types of reference frames, which can complicate the interpretation of neurophysiological data

Di(2-ethylhexyl) phthalate (DEHP), as one of the most broadly representative phthalic acid esters, is used as a plasticizer in Polyvinyl chloride production. The exact neurotoxicologically effects of DEHP to human have not been adequately researched. In order to investigate the effects and mechanisms of DEHP exposure on neural circuit, the spatial learning and memory of Sprague Dawley (SD) rats was measured, and the cellular mechanisms underlying synaptic plasticity, cellular excitability and ion channels were detected. Our data showed that the spatial learning and memory was changed by DEHP (100 and 300 mg) treatment. Meanwhile, the frequency of mini Excitatory Postsynaptic Current (mEPSC) from CA3 pyramidal cells were significantly decreased by DEHP exposure (0.1 and 0.3 M); the firing threshold, membrane potential threshold, number, amplitude and latency of Action Potentials (Aps) of CA1 pyramidal cells were altered with the application of DEHP (0.1 and 0.3 M); furthermore, DEHP, both in 0.1 and 0.3 M could inhibit the voltage-gated potassium channel of CA1 pyramidal cells. Our results indicated that DEHP could impair the spatial learning and memory, and this impairment might due to the DEHP-induced suppression of the neuronal excitability and synaptic plasticity by inhibiting the voltage-gated potassium channel, supporting the hypothesis that DEHP could cause the disruption of neural function.

Copyright: © 2008 Jackson et al.Background: Fluid and effective social communication requires that both face identity and emotional expression information are encoded and maintained in visual short-term memory (VSTM) to enable a coherent, ongoing picture of the world and its players. This appears to be of particular evolutionary importance when confronted with potentially threatening displays of emotion - previous research has shown better VSTM for angry versus happy or neutral face identities.Methodology/Principal Findings: Using functional magnetic resonance imaging, here we investigated the neural correlates of this angry face benefit in VSTM. Participants were shown between one and four to-be-remembered angry, happy, or neutral faces, and after a short retention delay they stated whether a single probe face had been present or not in the previous display. All faces in any one display expressed the same emotion, and the task required memory for face identity. We find enhanced VSTM for angry face identities and describe the right hemisphere brain network underpinning this effect, which involves the globus pallidus, superior temporal sulcus, and frontal lobe. Increased activity in the globus pallidus was significantly correlated with the angry benefit in VSTM. Areas modulated by emotion were distinct from those modulated by memory load.Conclusions/Significance: Our results provide evidence for a key role of the basal ganglia as an interface between emotion and cognition, supported by a frontal, temporal, and occipital network.The authors were supported by a Wellcome Trust grant (grant number 077185/Z/05/Z) and by BBSRC (UK) grant BBS/B/16178